package org.apache.lucene.analysis;

/**
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.io.BufferedReader;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;

/**
 * Loader for text files that represent a list of stopwords.
 *
 * @author Gerhard Schwarz
 * @version $Id: WordlistLoader.java 192989 2005-06-22 19:59:03Z dnaber $
 */
public class WordlistLoader {

    /**
     * Loads a text file and adds every line as an entry to a HashSet (omitting
     * leading and trailing whitespace). Every line of the file should contain only
     * one word. The words need to be in lowercase if you make use of an
     * Analyzer which uses LowerCaseFilter (like StandardAnalyzer).
     *
     * @param wordfile File containing the wordlist
     * @return A HashSet with the file's words
     */
    public static HashSet getWordSet(File wordfile) throws IOException {
        HashSet result = new HashSet();
        FileReader reader = null;
        try {
            reader = new FileReader(wordfile);
            result = getWordSet(reader);
        } finally {
            if (reader != null)
                reader.close();
        }
        return result;
    }

    /**
     * Reads lines from a Reader and adds every line as an entry to a HashSet (omitting
     * leading and trailing whitespace). Every line of the Reader should contain only
     * one word. The words need to be in lowercase if you make use of an
     * Analyzer which uses LowerCaseFilter (like StandardAnalyzer).
     *
     * @param reader Reader containing the wordlist
     * @return A HashSet with the reader's words
     */
    public static HashSet getWordSet(Reader reader) throws IOException {
        HashSet result = new HashSet();
        BufferedReader br = null;
        try {
            if (reader instanceof BufferedReader) {
                br = (BufferedReader) reader;
            } else {
                br = new BufferedReader(reader);
            }
            String word = null;
            while ((word = br.readLine()) != null) {
                result.add(word.trim());
            }
        } finally {
            if (br != null)
                br.close();
        }
        return result;
    }

    /**
     * @param path      Path to the wordlist
     * @param wordfile  Name of the wordlist
     *
     * @deprecated Use {@link #getWordSet(File)} instead
     */
    public static Hashtable getWordtable(String path, String wordfile) throws IOException {
        return getWordtable(new File(path, wordfile));
    }

    /**
     * @param wordfile  Complete path to the wordlist
     *
     * @deprecated Use {@link #getWordSet(File)} instead
     */
    public static Hashtable getWordtable(String wordfile) throws IOException {
        return getWordtable(new File(wordfile));
    }

    /**
     * @param wordfile  File object that points to the wordlist
     *
     * @deprecated Use {@link #getWordSet(File)} instead
     */
    public static Hashtable getWordtable(File wordfile) throws IOException {
        HashSet wordSet = (HashSet) getWordSet(wordfile);
        Hashtable result = makeWordTable(wordSet);
        return result;
    }

    /**
     * Builds a wordlist table, using words as both keys and values
     * for backward compatibility.
     *
     * @param wordSet   stopword set
     */
    private static Hashtable makeWordTable(HashSet wordSet) {
        Hashtable table = new Hashtable();
        for (Iterator iter = wordSet.iterator(); iter.hasNext();) {
            String word = (String) iter.next();
            table.put(word, word);
        }
        return table;
    }
}
